1. Technical Field
The present invention relates to a technique for recording a content which is recorded on a recording medium onto another recording medium, and particularly to an aggregation system for aggregating contents which are recorded on a plurality of recording mediums and recording them onto a single recording medium.
2. Background Art
With the advance of digital signal compression technology and recording technology, it has become common in recent years to sell contents which are digital copyrighted works, such as music, video and programs, recorded on recording mediums such as high-capacity optical discs like digital versatile discs (DVDs). It is possible to copy such digital contents recorded on the recording mediums to other recording mediums like hard disks and the like without deterioration in quality. Therefore, the copyrights of such contents are in danger of being infringed by unauthorized uses and copying thereof, and thus the solution of this problem has been demanded.
As one of the conventional methods for preventing unauthorized uses and copying by third parties, there is the Content Protection for Recordable Media (CPRM) standard, that is, a well-known scheme for preventing unauthorized copying of contents recorded on recording mediums (See, for example, “p. 7 of Matsushita Technical Journal, Vol. 48, No. 2 (April, 2002), issued on Apr. 18, 2002 by Matsushita Electric Industrial Co., Ltd.). This scheme will be briefly explained below.
First, on a recording medium manufactured in compliance with the CPRM standard, a medium ID that is unique to the recording medium is recorded when it is manufactured. This medium ID is the information which can be read but cannot be rewritten nor deleted. When a recording device manufactured in compliance with this standard records a content on a recording medium, it generates a content key by a predetermined method using the medium ID of the recording medium, and records, on the recording medium, the content encrypted by a predetermined method using the content key. Under this scheme, an encrypted content recorded on a recording medium A can be copied to another recording medium B. However, the medium ID of the destination recording medium B is different from the medium ID of the source recording medium A. Therefore, a reproduction device manufactured in compliance with this standard cannot obtain a content key for decrypting the encrypted content which has been recorded on the source recording medium A, even if it generates a content key by a predetermined method by reading the medium ID of the destination recording medium B. As a result, the content which is copied onto the recording medium B cannot be decrypted, and thus unauthorized copying can be prevented.
On the other hand, with the recent widespread of the Internet, various types of contents such as music and video have been obtained via the Internet. It is supposed, for example, that video and audio data are recorded on a DVD and a user who purchased the DVD can not only reproduce and view (and listen to) the video and audio data but also replace the audio data recorded on the DVD with another audio data obtained via the Internet and recorded on another recording medium. In this case, the wider the variety of replaceable audio data is, the more the variety of uses of the content recorded on the DVD increases, which enhances the commercial value of the content more and more.
Under these circumstances, it is expected to distribute contents not only via the above-mentioned recording mediums like DVDs but also in other manners for increasing the commercial value of the contents. For example, it may be possible for a user to obtain, via the Internet, a sub content which is to be used in association with a content recorded on a recording medium like a DVD, record the sub content on another recording medium (a hard disk, a high-capacity memory card or the like, for example), and reproduce the content by associating it with the sub content recorded on another recording medium.
It is also expected, in the above-mentioned content distribution manner, to distribute, as a sub content, the modification or addition data for the content recorded on a DVD and reproduce the content recorded on the DVD by associating it with the sub content so as to reproduce the updated content.
In this case, since the content and the sub content to be used in association with the content are recorded on separate recording mediums, a user has to carry a plurality of recording mediums to use these contents in various places. Therefore, it is anticipated, in the above-mentioned content distribution manner, that the use of these contents which are aggregated and recorded on another recording medium will be demanded for the sake of enhanced convenience of portability, for example. This type of usage results in actual copying of the content and the sub content if these contents recorded on separate recording mediums are just aggregated and recorded on another recording medium, because the content and the sub content can be reproduced from both of the source recording mediums and the destination recording medium on which the aggregated contents are recorded. Therefore, some measures must be taken in order to protect the copyrights of the contents.
However, the conventional technology like the CPRM standard is a scheme for preventing unauthorized copying of the contents recorded on a single recording medium in order to protect the copyrights of the contents, and there is no method for aggregating contents recorded on a plurality of recording mediums and recording them on another recording medium in order to enhance users' convenience, while at the same time protecting the copyrights of the contents.
The object of the present invention, in view of the above problem, is to provide an aggregation apparatus for aggregating contents recorded on a plurality of recording mediums and recording them on another recording medium while protecting the copyrights of the contents, a reproduction apparatus for reproducing the aggregated contents while protecting the copyrights of the contents, and an aggregation system for aggregating the contents while protecting the copyrights thereof or for reproducing the aggregated contents while protecting the copyrights thereof.
It should be noted that the above-mentioned aggregation or reproduction of contents under the protection of the copyrights thereof means the aggregation or reproduction of the contents based on the consent of the copyright owners to aggregate or reproduce the contents.